We intend to continue synthesis of new geometric isomers of vitamin A, A2 and related compounds, design stereoselective synthetic schemes to known isomers an to study properties of such new isomers. The latter will include investigation of photochemical properties of these polyenes, detailed structural studies including x-ray crystal structures and solution nmr studies. The aldehyde form of these new isomers and analogs will be prepared for preparation of the corresponding pigment analogs. A detailed analysis is expected to lead to a better understanding of the binding site of opsin. In the coming year we also expect to begin a systematic study on new geometric isomers of carotenoids.